(275b) Soluble ECM Modulates Drug Sensitivity and Invasion in Glioblastoma Spheroid Models

Glioblastoma (GBM) is the most common and aggressive form of brain cancer, with a median patient survival of less than 15 months. Elevated levels of extracellular matrix (ECM), such as collagen and hyaluronic acid (HA), are characteristic of the GBM tumor microenvironment. Interactions between GBM cells and ECM are known to play critical roles in tumor progression, including cancer invasion, therapeutic resistance, and immune cell infiltration. While insoluble ECM components, such as viscoelastic biopolymers, are widely used in engineered cancer models and have been shown to promote tumor angiogenesis, invasion, and chemoresistance, the effects of soluble ECM components circulating in the tumor microenvironment remain poorly understood.

To address this gap, we applied integrative bioengineering approaches to develop a library of GBM spheroid models incorporating either soluble collagen or HA fragments to assess their impact on tumor behavior. GBM cells (U87MG) were cultured in ultra-low attachment plates and exposed to soluble collagen or HA for up to two days prior to downstream analyses. We first evaluated the drug response of these spheroids to temozolomide (TMZ), the standard chemotherapeutic for GBM, to determine whether soluble ECM modulates pharmacological sensitivity. We also observed that routine medium replacement increased metabolic activity but did not affect drug sensitivity. Additionally, spheroids were embedded in gelatin-based hydrogels to assess invasive potential. We further profiled the secretome of each spheroid cohort to investigate the role of soluble ECM in regulating the release of soluble factors. Our results revealed that GBM spheroids treated with soluble collagen exhibited reduced metabolic activity compared to untreated controls, whereas HA treatment did not significantly alter metabolic activity. Notably, TMZ had limited efficacy in reducing the metabolic activity of HA-incorporated spheroids, suggesting that HA may attenuate GBM sensitivity to TMZ. Furthermore, GBM invasion was significantly decreased in collagen-treated spheroids compared to both untreated and HA-treated groups, indicating that collagen may promote a more quiescent GBM phenotype. Ongoing work is focused on characterizing ECM remodeling in these soluble ECM–incorporated GBM spheroids, as well as evaluating whether metronomic dosing regimens alter spheroid drug sensitivity. Collectively, this study provides new insights into the role of soluble ECM in GBM progression and underscores the importance of developing physiologically relevant microengineered tumor models for studying cancer biology.